I have TWO questions about travelling from Canada to Australia

Question One
The trip includes three flights. 1) Calgary to LA, 2) LA to Auckland, and 3) Auckland to Brisbane. I am a little worried on the Auckland to Brisbane flight because I only have a 2 hour layover from the moment my plane is schedule to land, to the moment my plane for Brisbane is supposed to take off. Is that enough time to clear customs (if I have to?), and get there? I am not bringing any baggage, just carry ons. Should I be worried about this?

Question 2
Who offers the most favourable exchange rates? I have some US currency I can exchange, as well as Canadian, but I am reluctant to do it at the banks here in Canada. Theyre charging me close to 7 or 8 cents on the dollar… its insane. Do airports really offer the best exchange rates?

Also… BQ:

That flight from LA to Auckland is about 13 hours… and thats after a 7 hour layover in LA. What should I do to cope with that? Any tips?